1. Field of the Invention
The invention relates to a cooling structure of a cylinder block, and more particularly to a cooling structure of a cylinder block, which makes it possible to uniformly cool the cylinder block.
2. Description of the Related Art
A conventional cooling structure of a cylinder block is disclosed, for example, in Japanese Patent Laid-Open Publication No. 2002-30989.
In the conventional cooling structure of a cylinder block disclosed in the Japanese Patent Laid-Open Publication No. 2002-30989, a temperature of a bore wall is made uniform in a circumferential direction of a bore by inserting a water jacket spacer which is separate from a cylinder block in a water jacket of the cylinder block.
However, even in the aforementioned technology, the temperature of the bore wall cannot be made sufficiently uniform.
Further, even when a drill path is provided in a portion which coolant does not directly contact, and whose temperature becomes high, an inter-bore region which is positioned in the vicinity of a boundary between bore regions adjacent to each other is not sufficiently cooled. This is thought to be because the water jacket spacer obstructs an inlet of the drill path, and therefore a flow rate of the coolant in the drill path is reduced.